Prior art disclosing polymerizable blocked isocyanates is as follows: U.S. Pat. Nos. 2,483,194; 2,556,437; 2,882,260; 3,261,817; 3,299,007; 3,542,739 and 3,694,146, and British Patent 1,288,225. Other relevant art is disclosed in U.S. Pat. Nos. 3,519,478; 3,694,389 and 3,711,571.
The novel ethylenically unsaturated blocked aromatic diisocyanates can be distinguished from other known polymerizable isocyanates by their ease of polymerization and copolymerization with vinylidene monomers, particularly in emulsion polymerization systems. The prepared polymers are quite stable to hydrolysis and can be stored in latex form.
Interpolymers of the novel diisocyanates with acrylate monomers have particular utility as binders for non-woven fibers such as paper, cotton, synthetic fibers, and the like. The fibers are coated or impregnated with the interpolymers which can then be cured at temperatures as low as 80.degree. C. and under acidic, neutral, or basic pH conditions. This is in contrast to the known acrylic or nitrile latex binders which require highly acidic (pH of about 2) conditions to exhibit a strong fast cure at low temperatures. The highly acidic environment is undesirable as it can degrade some fibers, especially cellulose-type fibers, it can interfere with efforts to thicken the latex for more convenient use, and it can cause corrosion.